四种单宁植物形成层的活动周期和次生韧皮部的季节变化

PERIODICITY OF CAMBIUM ACTIVITY AND SEASONAL CHANGES OF THE SECONDARY PHLOEM IN FOUR TANNIN PLANTS

余甘子ＰｈｙｌａｎｔｈｕｓｅｍｂｌｉｃａＬ．杨梅Ｍｙｒｉｃａｒｕｂｒａ（Ｌｏｕｒ．）Ｓｉｅｂ．ｅｔＺｕｃｃ．黑荆树Ａｃａ－ｃｉａｍｅａｒｎｓｉＤｅＷｉｌｄｅ形成层的活动有明显的季节性。形成层活动期分别为５～１１月，３～１２月，２～１０月。其他时间休眠。细枝木麻黄ＣａｓｕａｒｉｎａｃｕｎｎｉｎｇｈａｍｉａｎａＭｉｑ．的形成层周年都在活动，１，２月的材料中也见到成膜体。４种树木在冬季都保留相当数量的具功能韧皮部，其宽度为０．２～０．３ｍｍ。

There is definitely seasonal activity in cambial growthes in the Phyllanthus emblica, Myrica rubra, Acacia mearnsii, The periods of cambial activity are respectively from May to November, March to December and February to October. These cambia are dormant in other time in a year. The cambium of Casuarina cunninghamiana is active all year round. There are phragmoplasts in tangential sections of cambium in January and February. During dormancy of cambia, every species retains rather wide functional phloem (0.2～0.3 mm in width).